In collaboration with faculty and staff at the UNC School of Medicine, OptoSonics proposes to develop and validate a new clinical imaging platform for breast cancer screening in patient populations for whom X-ray mammography is less sensitive. This platform will allow clinicians to assess two distinct biomarkers of breast cancer - hemoglobin distribution and blood flow within suspicious masses - in women with dense breast, women < 50 years of age, and those with a genetic or familial predisposition to breast cancer. Two new imaging technologies will be integrated into a single platform: 3D photoacoustic computed tomography (PAT) for imaging optical absorption; and, Dynamic, contrast-enhanced PAT (DCE-PAT) for quantifying blood flow and perfusion in suspicious masses. Both modalities will be co-registered spatially as they share conformal detector geometries. Our goal is to demonstrate 1.0 millimeter spatial resolution for imaging hemoglobin throughout the whole breast, compressed against the chest wall to < 5 cm, and to quantify blood flow within suspicious masses with spatial resolution 0.5 mm. The clinical utility of this new imaging technology will be evaluated through several, clinical studies.